Signal carrying apparatus

ABSTRACT

A signal carrying apparatus ( 101 ) for transmitting a signal by variation of electromagnetic field comprises a meshed first conductor portion ( 111 ) which serves as a conductor in the frequency band of the electromagnetic field, and a second conductor portion ( 121 ) of which external shape is sheet-like and which serves as a conductor in the frequency band of the electromagnetic field and arranged substantially in parallel with the first conductor portion ( 111 ). In the interval region ( 131 ) between the external shape of the first conductor portion ( 111 ) and the external portion of the second conductor portion ( 121 ), and in the planar leak region ( 141 ) located oppositely to the interval region ( 131 ) across the external shape of the first conductor portion ( 111 ), the electromagnetic field propagating in that frequency band has a strength attenuating exponentially with the distance from the external shape of the first conductor portion ( 111 ) in the leak region ( 141 ).

TECHNICAL FIELD

The present invention relates to a signal carrying apparatus fortransmitting a signal by variation of electromagnetic field in theinterval region between a meshed conductor portion and a sheet-likeconductor portion and the leak region outside the meshed conductorportion side.

BACKGROUND ART

Inventors of the present application have been proposing technologiesfor a sheet-like (cloth-like, paper-like, foil-like, plate-like,film-like, or mesh-like, one dimensioned as a plane but having a thinthickness) communication device having a plurality of communicationelements embedded therein. For example, the following literaturediscloses a communication device having a plurality of communicationelements, embedded in a sheet-like member (hereinafter, a “sheet-likebody”), relay a signal without individual wirings, thereby transmittingthe signal.

Patent Literature 1: Japanese Unexamined Patent Application KOKAIPublication No. 2004-007448

According to the technology disclosed in the [patent literature 1],communication elements are disposed at respective vertexes of a figureformed in a grid-like shape, a triangular shape, or a honeycomb-likeshape on the surface of the sheet-like body. A communication elementutilizes a change in a potential, which is generated by thecommunication element and propagates strongly nearby but attenuatesdistantly, and communicates another communication element only.

By successively transmitting a signal between individual communicationelements through local communications, the signal is transmitted to atarget communication element. The plurality of communication elementsare hierarchized by a management function, path data is set for eachhierarchy, so that a signal is efficiently transmitted to afinal-destination communication element.

On the other hand, developed through the researches of the inventors isa technology such that an electromagnetic field is generated at a regionsandwiched between sheet-like bodies facing with each other, and theelectromagnetic field is made progress by changing the electromagneticfield through a change in a voltage between the two sheet-like bodies,and by changing the voltage between the sheet-like bodies through achange in the electromagnetic field, thereby performing communication.

To detect a voltage between the two sheet-like bodies, in general, acommunication device is directly connected to both sheet-like bodies viawires, and the sheet-like body is provided with a connector which is tobe connected to the communication device.

DISCLOSURE OF INVENTION Problem to be Solved by the Invention

However, if such wired connection is avoided as much as possible and thesheet-like body is made to be capable of transmitting a signal by movingan external communication device closer to the sheet-like body, itbecomes user-friendly, and the maintenance efficiency becomes improved.

Then, a new technology for coping with such a request is stronglyrequired.

The present invention responds to this request, and the purpose of thepresent invention is to provide a signal carrying apparatus fortransmitting a signal by variation of electromagnetic field in theinterval region between a meshed conductor portion and a sheet-likeconductor portion and the planar leak region on the external side of themeshed conductor portion.

Means for Solving the Problem

In order to achieve the afore-mentioned object, the below-mentionedinvention is disclosed in accordance with the principle of the presentinvention.

The signal carrying apparatus of the present invention carries a signalby variation of electromagnetic field and an interface device fortransmitting the signal between the interface device and the signalcarrying apparatus, and is configured as below.

Namely, the first conductor portion serves as a conductor in thefrequency of the electromagnetic field and is of a meshed shape.

On the other hand, the second conductor portion is disposed insubstantially parallel with the first conductor portion, serves as aconductor in the frequency band of the electromagnetic field, and theexternal shape is sheet-like.

Further, the electromagnetic field is transmitted in the frequency bandin the interval region sandwiched between the external shape of thefirst conductor portion and that of the second conductor portion and theleak region of the planar external shape positioned oppositely whichsandwiches the external shape of the first conductor portion with theinterval region.

Then, of the electromagnetic field in the leak region, the strength ofthe traveling wave component that is affected by the meshed shape isexponentially attenuated with the distance from the external shape ofthe first conductor portion.

In addition, in the signal carrying apparatus of the present invention,the repeated unit length of the meshed shape is d and the thickness ofthe leak region can be constituted to be d even if it is the maximumvalue.

In addition, in the signal carrying apparatus of the present invention,the average width of the mesh size in the meshed shape is d and can beconstituted to be d even if it is the maximum value.

In addition, in the signal carrying apparatus of the present invention,the meshed shape is a mesh one that repeats polygons of the same shape,the repeated unit length is d, of the electromagnetic field in the leakregion, the strength of the traveling wave component that is affected bythe meshed shape can be so configured as to be attenuated withcoefficient of e^(−2πz/d) or less relative to the distance z to the leakregion from the external shape of the first conductor portion.

In addition, in the signal carrying apparatus of the present invention,the shape of the meshed portion is a mesh one such that a plurality ofcircular holes are provided in a flat plate, the central distances ofthe circular holes are each d, of the electromagnetic field in the leakregion, the strength of the traveling wave component that is affected bythe meshed shape can be so configured as to be attenuated withcoefficient of e^(−2πz/d) or less relative to the distance z to the leakregion from the external shape of the first conductor portion.

In addition, it can be configured such that in the signal carryingapparatus of the present invention, the variation of the electromagneticfield is transmitted to the antenna disposed in the leak region from theinterval region and leak region, or the variation of the electromagneticfield is transmitted to the interval region and leak region from theantenna, thereby communicating with an external device connected to theantenna.

Particularly, as external devices, a chip of RFID tag or various kindsof sensors can be also adopted.

In addition, it can be configured such that in the signal carryingapparatus of the present invention, the voltage between the firstconduction portion and the second conduction portion varying with theelectromagnetic field in the interval region and the leak region istransmitted to a communication device connected to the first conductionportion and the second conduction portion in wired connection, orsignals are transmitted between the communication device and theexternal device by varying the voltage between the first conductionportion and the second conduction portion to vary the electromagneticfield in the interval region and the leak region.

In addition, in the signal carrying apparatus of the present invention,it can be configured such that the second conductor portion is a meshedshape, and the electromagnetic field is further transmitted in thefrequency band in the planar shaped opposite region oppositelypositioned that sandwiches the external shape of the second conductorportion with the interval region.

In addition, in the signal carrying apparatus of the present invention,it can be configured such that the first conduction portion is a stripedshape in place of the first conduction portion being a meshed one.

EFFECT OF THE INVENTION

The present invention can provide the signal carrying apparatus thattransmits a signal by variation of electromagnetic field in the intervalregion between the meshed conduction portion and the sheet-likeconduction portion and the leak region outside the meshed conductionportion.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram showing a schematic configuration of asignal carrying apparatus used in combination with an interface deviceof an embodiment according to the present invention;

FIG. 2 is an explanatory diagram showing the condition of the interfacedevice of the simplest shape to the signal carrying apparatus of theembodiment;

FIG. 3 is an explanatory diagram showing a schematic configuration ofthe signal carrying apparatus used in combination with the interfacedevice of the embodiment according to the present invention;

FIG. 4 is an explanatory diagram showing the condition of the coordinatesystem used to analyze the signal carrying apparatus;

FIG. 5 is an explanatory diagram showing the strength of a verticalelectric field at various places in the signal carrying apparatus;

FIG. 6 is an explanatory diagram showing the directivity of anelectromagnetic field;

FIG. 7 is an explanatory diagram showing a schematic configuration ofone embodiment of the interface device having directivity;

FIG. 8 is an explanatory diagram showing a relationship between t valuesand w values in the interface device;

FIG. 9 is an explanatory diagram showing a general shape of the side ofan internal conductor portion connected to a path conductor portion;

FIG. 10 is an explanatory diagram showing parameters of the shape of theinterface device;

FIG. 11 is an explanatory diagram showing the condition of anelectromagnetic field generated in a region in the vicinity of theinternal conductor portion;

FIG. 12 is an explanatory diagram showing the condition of theelectromagnetic field in φ₁ mode;

FIG. 13 is an explanatory diagram showing a schematic configuration of acircular interface device;

FIG. 14 is an explanatory diagram showing a schematic configuration ofthe circular interface device;

FIG. 15 is an explanatory diagram showing the other embodiments of theinterface device;

FIG. 16 is an explanatory diagram showing the relationship of theparameters and the conditions of current and magnetic field;

FIG. 17 is an explanatory diagram showing a method for performingimpedance alignment;

FIG. 18 is explanatory diagram showing experimental parameters of thesignal carrying apparatus and the interface device;

FIG. 19 is a graph showing a receiving power in case the interfacedevice is allowed to gradually go away from the interface transmitter;

FIG. 20 is a graph showing the other receiving power in case thedirection to one mesh of two interface devices is varied;

FIG. 21 is a graph showing the other receiving power in case theposition of one interface device of the two interfaces is moved;

FIG. 22 is an explanatory diagram showing a cross-section of the otherembodiment of the interface device;

FIG. 23 is a cross-section showing a relationship between the interfacedevice and a signal carrying apparatus of the other embodimentconnectable to the former;

FIG. 24 is an explanatory diagram in case a wired connection isconducted onto the signal carrying apparatus; and

FIG. 25 is an explanatory diagram showing an embodiment of the signalcarrying apparatus with the first striped conduction portion in place ofa meshed one.

EXPLANATION OF REFERENCE NUMERALS

-   101 Signal Transmitter-   111 First Conductor Portion-   121 Second Conductor Portion-   131 Interval Region-   141 Leak Region-   151 Opposite Region-   201 Communication Circuit-   202 Loop Antenna-   203 Dipole Antenna-   601 Interface Device-   602 Internal Conductor Portion-   603 External Conductor Portion-   604 Path Conductor Portion-   605 Insulator Portion-   606 Connection Point-   901 Conductor Plate-   902 Coaxial Cable-   903 Junction Portion-   904 Striped Conduction Portion

BEST MODE FOR CARRYING OUT THE INVENTION

The embodiment of the present invention is described below. In addition,the description of the embodiment is for explanation purpose only, anddoes not limit the scope of the present invention. Therefore, those whoare skilful in the art can adopt embodiments where each factor or allthe factors thereof are replaced with new ones which are equal to thosein the present invention. However, these embodiments are also includedin the scope of the present invention.

The planar shaped signal carrying apparatus and the interface device foracquiring and carrying signals by allowing the interface device to beput closer to the signal carrying apparatus are sequentially describedbelow.

In addition, for easier understanding, a conductor which is in afrequency band of electromagnet field used for a signal transmission ishereinafter referred to as “a conductor” and a dielectric which is inthe frequency band is hereinafter referred to as “a dielectric”.Therefore, for example, a matter which is an insulator to direct currentmay be also referred to as “a conductor”.

Embodiment 1 Signal Transmitter

FIG. 1 is an explanatory diagram showing a schematic configuration ofthe signal carrying apparatus of the embodiment and is described withreference to the diagram below.

The diagram (b) is a cross-section of the signal carrying apparatus 101of the embodiment. As shown in the diagram, the signal carryingapparatus 101 is provided with the meshed first conductor portion 111and the planar second conductor portion 121 substantially in paralleltherewith.

Here, a region between the first conductor portion 111 and the secondconductor portion 121 is the interval region 131, and a region on thefirst conductor portion 111 in the diagram is the leak region 141.

The diagram (a) is a plan view of the signal carrying apparatus 101. Thefirst conductor portion 111 of the embodiment is of a mesh of squares,and the second conductor portion 121 is shown through in the square.

In addition, the repeated unit is equal to the centers of the squaresthat are horizontally adjacent to each other and these are almost equalto the length of one side of the square.

In the embodiment, the interval region 131 and the leak region 141 areeach of the air. However, any or both of them may be of various kinds ofdielectrics, water, soil, or vacuum.

The external shapes of the first conductor portion 111 and the secondconductor portion 121 are each sheet-like materials (cloth-like,paper-like, foil-like, planar, membranous, film-like, and the like,which are each broad as a surface and the thicknesses are each small).

Therefore, for example, if the wall of a chamber should be the signalcarrying apparatus of the embodiment, a sheet of metal foil is firstaffixed as the second conductor portion 121, an insulator is thensprayed, a metallic mesh is affixed as the first conductor portion 111,and a wall paper of insulator may be further affixed.

Then, an attention should be thus paid to an electromagnetic wave modepropagating in the interval region 131 between the first conductorportion 111 and the second conductor portion 121 in the signal carryingapparatus 101.

Supposing that the first conductor portion 111 is not of mesh, and is ofa structure without a foil-like aperture, the electromagnetic wave iscompletely contained in the interval region 131.

However, the first conductor portion 111 has a meshed structure with anaperture. In such a shape, the electromagnetic wave is liable to leak bya height almost equal to the distance of the mesh. A region in which theelectromagnetic wave leaks is the leak region 141.

The height (thickness) of the leak region 141 is almost the same as inthe repeated unit of the mesh. Actually, the strength of theelectromagnetic wave is liable to exponentially attenuate correspondingto a distance of the surface of the first conductor portion 111.

FIG. 2 is an explanatory diagram showing the condition of the interfacedevice of the simplest shape to the signal carrying apparatus of theembodiment. In the diagram, there is shown the condition thatcommunications are performed between the interface device and the signalcarrying apparatus 101 by arranging a loop antenna or a dipolar antennaas the interface device. It is described with reference to the diagrambelow.

The diagram shows four combinations of the communication circuit 201that performs transmitting/receiving and the loop antenna 202 connectedto the communication circuit in the leak region 141 present on thesurface of the meshed first conductor region 111.

It is preferable that the length of the loop antenna 202 is almost halfof the length of the electromagnetic wave transmitted by the signalcarrying apparatus 101. However, even if it is larger or smaller thanthis one, communications are possible.

The diagram shows a case that an antenna is vertically disposed on thesurface of the first conductor portion 111 if the longitudinal loopantenna 202 is disposed in parallel with the surface of the firstconductor portion 111.

In addition, the diagram shows a case that both ends of the horizontallyset U-shaped loop antenna 202 are terminated by the communicationcircuit 201 and is disposed in parallel with the surface of the firstconductor portion 111.

Furthermore, the diagram shows a case that a shaped one such that thehorizontally set U-shaped loop antenna 202 is connected to thecommunication circuit 201 and its end is further extended up to theopposite side of the communication circuit 201 is vertically disposed onthe surface of the first conductor portion 111.

In addition to the afore-mentioned, the interface device using thedipolar antenna 203 where the core wire of a coaxial cable is merelyexposed is also illustrated. In this case, it is possible to receive theelectromagnetic wave between the communication device and the signalcarrying apparatus 101 connected to the coaxial cable by putting thecore wire of the dipolar antenna 203 closer to the first conductorportion 111.

It is possible to perform communications between these communicationcircuits 201, or to perform communications between the communicationdevice and the communication circuit 101 connected to the coaxial cablethrough the signal carrying apparatus 201. In addition, even if it isnot shown in the diagram, it is also possible to communicate with acommunication device if the communication device directly connected inwired connection to the first conductor portion 111 and the secondconductor portion 121 is provided. Thus, any of 1 versus 1, 1 versus N,N versus 1, N versus N is also possible.

Further, the device can be used as a read-out device of a tag using acircuit of RFID tag as the communication circuit 201, further a sensorcan be mounted thereon. In addition, there provides also a form of usagethat it is connected to an external device by wiring from thecommunication circuit, and it is connected to a coaxial cable to connectit to the external device in place of being connected to thecommunication circuit.

In addition, it is also possible to charge the interface device sidewith a micro wave to supply an electric power.

In addition, the second conductor portion 121 is determined to be afoil-like conductor without any aperture. However, the second conductor121 may be of a mesh as in the first conductor portion 111. FIG. 3 is across-section related to such a configuration.

As shown in the diagram, the opposite region 151 equivalent to the leakregion 141 is present also outside the second conductor portion 121 andthe electromagnetic wave is liable to leak also here. Therefore, theelectromagnetic wave leaks on both of the front surface and backside, itis possible to receive signals if the interface device is put closer toany of the surfaces.

Then, such a theoretical background of the leak region 141 is brieflydescribed below. In the signal carrying apparatus 101 in such aconfiguration as afore-mentioned, the mode φ_(n) of the electromagneticwave propagating without “radiating” the electromagnetic wave outsidethe signal carrying apparatus 101 is existent in the interval region 131(the leak region 141 and opposite region 151 that are in the vicinitythereof).

Here, the height L of a near-field where the electromagnetic field ofalmost the same strength as in the interval region 131 leaks and thereis no electromagnetic radiation to a distance is L=about d/(2π) when therepeated unit length of mesh is assumed as d.

Here, the amplitude of the electromagnetic wave that leaks attenuatesalmost as in e^(−z/L) if a distance from the surface of the firstconductor portion 111 or the second conductor portion 121 is assumed asz in the leak region 141 or the opposite region 151.

Therefore, the interface device is disposed in the scope of the distanceL from the first conductor portion 111 (or the second conductor portion121) and φ_(n) is induced to transmit a signal. In addition, the scopemay be about the length d in place of the distance L depending upon thesensitivity of the interface device. Namely, it can be considered thatthe thickness of the leak region 141 (or the opposite region 151) isabout L to d.

It is further considered in detail below. FIG. 4 is an explanatorydiagram showing the condition of the coordinate system used to analyzethe signal carrying apparatus 101. It is described with reference to thediagram below.

As shown in the diagram, it is assumed that the meshed first conductorportion 111 where the repeated unit length is d is disposed at z=0 andthe second conductor portion 121 is disposed at z=−D. Then, it isassumed that other than the first conductor portion 111 and the secondconductor portion 121 are filled with dielectrics of dielectric constant∈. It is assumed that a mesh is a mesh of squares. The original point issuperposed on the mesh intersection, and the x axis and the y axis arein parallel with the mesh.

Then, electromagnetic energy is locally present in the vicinity of themeshes, the traveling wave solution in the form of E_(z)=Af(x, y, z) exp(−j(xk_(x)+yk_(y))) relative to the electric field E out of theelectromagnetic field. Here, E_(z) is the z component of the electricfield, A, k_(x), and k_(y) are each constant, and f(x, y, z) is afunction having a cycle d in the x direction and the y direction,k=(k_(x), k_(y), 0) is a wave vector (propagation vector) showing thetraveling direction of the traveling wave.

Namely, f(x+d, y, z)=f(x, y, z)=f(x, y+d, z) is established relative toarbitrary x, y, z.

Then, the electromagnetic field including E_(z) meets the wave equation:

ΔE _(z)=−(ω² /c ²)E _(z) in the dielectric and k _(x) ² +k _(y)²≈(nearly equal)ω² /c ².

Here, if an attention is paid to the electromagnetic field at z>0, thefollowing Fourier expansion of f is possible with the cyclicality of f:

f(x,y,z)=Σ_(m,n) a(m,n)exp(2πjmx/d)exp(2πjny/d)g(m,n,z)

wherein, m and n are integers.

If d is sufficiently smaller than the wavelength of the electromagneticwave λ, 2π/d is sufficiently larger than ω/c, the component:

u(m,n)=exp(2πjmx/d)exp(2πjny/d)g(m,n,z)

approximately meets Δu=(−(2πm/d)²−(2πn/d)²+∂²/∂z²)u=0, that is,

∂²/∂z²g≈(2π)²(m²+n²)/d²g from the independency of each component ofFourier expansion in the case of (m,n)≠(0,0). Therefore, it is

g(m,n,z)≈Bexp(−2π(m ² +n ²)^(1/2) z/d).

wherein, B is a constant. Therefore, of the component of (m,n)≠(0,0),its attenuation coefficient is d/(2π) or less.

Here, the component of (m,n)#(0,0) is equivalent to the component of thetraveling wave where the cycle of the meshed structure is modulated.

In addition, the component equivalent to (m,n)#(0,0), namely, thecomponent of the traveling wave where the cycle of the meshed structureis not modulated reaches up to about the wavelength λ=2π/(k_(x) ²+k_(y)²)^(1/2). However, its strength is small. This component is a componentthat is directly related to the item exp(−j(xk_(x)+yk_(y))).

The vertical electric field E₂[V/m] generated when the first conductorportion 111 is determined to be a mesh-shaped conductor with square meshnetwork of d=2 [mm], the second conductor portion 121 is determined tobe a foil-like conductor, and mean line charge density σ=1[C/m] is givento the first conductor portion 111 in accordance with such as atheoretical background is multiplied by coefficient 4π∈, thereby findingthe product.

As in the afore-mentioned, the first conductor portion 111 is disposedat z=0 and the second conductor portion 121 is disposed at z=−D. Theoriginal point is superposed upon the mesh intersection, and the x axisand the y axis are in parallel with the meshes.

FIG. 5 is an explanatory diagram showing the strengths of the verticalelectrical fields at various places in the signal carrying apparatus inthis case. It is described with reference to the diagram below.

As shown in three graphs in the upper row of the diagrams, it isunderstood that the vertical electrical field becomes almost 0 from thevicinity of z=1[mm] in any of (x,y)=(0,0), (x,y)=(d/2,d/2),(x,y)=(d/2,0). In addition, the vertical electrical fields at y=1[mm]and z=0.2 [mm] each become a cyclic pattern as shown in one graph in thelower row of the diagram.

Thus, because it is considered that the leak of the electromagneticfield is about 1 mm when the repeated unit length of the mesh is 2 mm,it is considered that induction between the mesh and the electromagneticfield becomes possible to transmit and receive signals if the interfacedevice is put closer to the meshes in the distance or less.

In addition, the electrical field distribution in the case where themesh structure of the second conductor portion 121 disposed at z=−D isthe same as in the first conductor portion 111 disposed at z=0 is thesame distribution as in the case where the foil-like second conductorportion 121 is disposed at z=−D/2 and the meshed first conductor portion111 is disposed at z=0, in accordance with the principle of symmetry.Therefore, a similar conclusion as the afore-mentioned is obtained.

Thus, about d/(2π) to d/2 to d order is considered sufficient as thethickness of the interval region 141 or the opposite region 151, andcommunications can be performed by “dipping” an interface into the leakregion 141 or the opposite region 151.

In addition, the component corresponding to (m, n)=(0,0) may leak up toabout the electromagnetic wavelength λ=2π/(k_(x) ²+k_(y) ²)^(1/2) in acommunication layer. However, because the strength of the component isweaker than those of others in the vicinity of the surface in thecommunication layer, the strength thereof can be ignored.

In addition, the mesh needn't to be inevitably the repetition ofsquares, and may be of various polygonal shapes. In addition, the unitof the mesh needn't to be inevitably limited to the same shape, if it isof appropriately formed meshes, and it may be of a different shape. Inthis case, it is considered that a value equivalent to theafore-mentioned d is an average one of each mesh. In addition, if thesebasic cycles are present, it can be also considered that the cycle is d.

Besides the afore-mentioned, a portion where a plurality of punchedcircular holes are arranged in a honeycomb form in a planar conductormay be used as the first conductor portion 111. In this case, thedistances of the centers of circles are equivalent to theafore-mentioned d.

(Interface Device)

In the afore-mentioned descriptions, the loop antenna 202 or the dipolarantenna 203 is used in the interface device. However, an interfacedevice such that electromagnetic field having directivity can beradiated is proposed below.

In addition, it is preferable that the interface device proposed here isused in a combination with the afore-mentioned signal carrying apparatus101. However, if it can contact the electromagnetic field that transmitsthe signal, communications are possible. Therefore, aspects that theinterface device is used are not limited to a combination with theafore-mentioned signal carrying apparatus 101.

FIG. 6 is an explanatory diagram for explaining the directivity of suchan electromagnetic field. It is described with reference to the diagram.

As shown in the diagram, if it is assumed that an angle around the zaxis vertically set to the first conductor portion 111 and the secondconductor portion 121 in the signal carrying apparatus 101 is θ, theelectromagnetic field φ₁ radiated by the interface device of theembodiment is as follows:

E _(z) ≈e(r,z)cos θ;

B _(θ≈) b(r,z)cos θ;

wherein, r²=(x²+y²)if it is assumed that the electromagnetic field in the z direction isE_(z) and the magnetic field component in the counterclockwise directionof the z axis is B_(θ).

FIG. 7 is an explanatory diagram showing a schematic configuration ofone embodiment of the interface device having such directivity. It isdescribed with reference to the diagram below.

The interface device 601 can be mostly divided into the internalconductor portion 602, the external conductor portion 603, and the pathconductor portion 604.

The internal conductor portion 602 is a conductor that is being putcloser to the signal carrying apparatus 101, is of a strip-like shape ofwidth t, and one end thereof is connected to the external conductorportion 603 and the other end is connected to the path conductor portion604, respectively.

The external conductor portion 603 is of a box-like structure thatcovers the internal conductor portion 602. An aperture is provided inthe external conductor portion 603 and the path conductor portion 604passes through the aperture noncontactly.

This allows a current path of the external conductor portion 603 to theinternal conductor portion 602 to the path conductor portion 604 to beestablished. Then, if the coaxial cable or the signaltransmitting/receiving circuit is connected to the external conductorportion 603 and the path conductor portion 604 in the vicinity of theaperture of the external conductor portion 603 to vary the currentflowing here, the electromagnetic wave is mainly radiated in thedirections of the arrows in the diagram.

Thus, electromagnetic energy can be efficiently received between theinterface device and the signal carrying apparatus 101, because auseless electromagnetic radiation outside the interface device 601 canbe prevented by covering the internal conductor portion 602 and the pathconductor portion 604 with the external conductor portion 603.

In addition, portions other than the external conductor portion 603, theinternal conductor portion 602, and the path conductor portion 604 maybe filled with dielectric. In addition, of the external conductorportion 603, the internal conductor portion 602, and the path conductorportion 604, each surface whose outer surface thick portion only shouldbe a conductor and each of their internal materials may be arbitraryones.

It is desirable that the mutually opposed surfaces of the externalconductor portion 603 and the internal conductor portion 602 are inparallel and the internal conductor portion 602 is also of a planarstrip. Steps and irregularities may be allowable.

It is desirable that t is not extremely larger than w if a distancebetween the mutually opposed surfaces of the external conductor portion603 and the internal conductor portion 602 is assumed as w. Namely, itis desirable that t is almost the same as w or is w or less.

FIG. 8 is an explanatory diagram showing a relationship between t and win the interface device 601. It is described with reference to thediagram.

If t is almost the same as w or is w or less, the electromagnetic fieldgenerated by allowing the current to flow in the internal conductorportion 602 is also generated outside the interface device 601 (thehatched region on the right in the diagram), and the electromagneticfield is coupled with the traveling wave mode of the signal carryingapparatus 101, thereby enabling the system to induce the traveling wave.

On the other hand, if t becomes larger to cover the entire bottom of theinterface device 601, transmitting/receiving signals can not becompletely performed.

However, if a clearance is opened at a part of the bottom, a couplingwith the traveling wave mode of the interval region 131 in the signalcarrying apparatus 101 occurs. Then, there is also considered a casethat t is more enlarged than w to decrease the impedance when the insideof the interface device 601 is viewed from the aperture of the externalconductor portion 603 (which is a junction of the cable and theinterface device 601), if impedance alignment is arranged with the cableand the communication circuit that drive the interface device 601.

However, in this case, the percentage of the energy accumulated in thehatched region S on the left hand in the diagram to the electromagneticenergy generated outside the interface device 601 becomes big, thusextra energy loss would occur due to the dielectric loss in the firstconductor portion 111 contacting the region S and the region S.

Therefore, a method wherein t per se is not enlarged, and whereinimpedance alignment is performed can be adopted so as to allow theinternal conductor portion 602 to include a plurality of thin bands.FIG. 9 is an explanatory diagram showing a general shape of the side tobe connected to the path conductor portion 604 in the internal conductorportion 602 in such a case.

As shown in the diagram, the internal conductor portion 602 is of afork-like shape and, it is configured such that a plurality of thinbands are extended from the path conductor portion 604 and are connectedto the external conductor portion 603 (not illustrated in the diagram).

In addition, it is desirable that 2πR is not extremely smaller than Xrelative to the length R of the internal conductor portion 602 (thedistance between the point where the internal conductor portion 602 isconnected to the external conductor portion 603 and the point where theinternal conductor portion 602 is connected to the path conductorportion 604 is R-m) and the wavelength λ of the electromagnetic field.

Here, λ is the wavelength 2π/(K_(z) ²+k_(y) ²)^(1/2) of the travelingwave in the signal carrying apparatus 101.

Supposing that 2πR<<λ is established, this is because the percentage ofenergy loss (caused by the dielectric loss in the surroundings of theinterface device and the resistance of metals) when the electromagneticwave is transmitted to the signal carrying apparatus 101 becomes large,since the percentage of energy that is radiated in a distancesignificantly becomes small to the electromagnetic energy locallygenerated in the vicinity of the current path.

By the way, the interface device 601 in such a general shape can beconnected to the afore-mentioned signal carrying apparatus 101 and canbe also connected to a signal carrying apparatus where two sheet-likeconductors are opposed and apertures are locally provided and a signalcarrying apparatus where a sheet-like dielectric is affixed onto onesheet of sheet-like dielectric. Therefore, the interface device 601 canbe applied to various signal carrying apparatuss.

The electromagnetic field generated by the interface device 601 isfurther examined in detail below.

FIG. 10 is an explanatory diagram showing the parameters of the shape inthe interface device 601. They are described with reference to thediagram.

It is assumed that the length of the internal conductor portion 602(hereinafter suitably referred to as “proximity path”) is R, thedistance between the internal conductor portion 602 and the externalconductor portion 603 is w, and the length of the internal conductorportion 602 that is further extended over the connection point with thepath conductor portion 604 is m.

FIG. 11 is an explanatory diagram showing the condition of theelectromagnetic field generated in the region S in the vicinity of theinternal conductor portion 602 under such conditions.

R, m, w, and t are controlled so as to allow the impedance of thecoaxial cable connected to the interface device 601 and the impedancewhen the inside of the interface device 601 is viewed from the portionto which the coaxial cable is connected to be closer to each other.Here, there is a place where the reactance components of the impedanceare zero intersected when R≈λ/4. Then, the length of R is set at a placewhere the reactance components are zero intersected.

Next, m, t, and w are simultaneously controlled so as to allow theactual portion of the impedance to be an impedance of the coaxial cable.

The electromagnetic field of such φ₁ mode is generated. However, FIG. 12is an explanatory diagram showing the condition of the electromagneticfield in the φ₁ mode. It is described with reference to the diagrambelow.

The rectangles shown in the upper and lower rows of the diagram areequivalent to the internal conductor portion 602. In addition, theexternal conductor portion 603 is in the circular shape shown in thedotted lines.

The upper row of the diagram shows the condition of the distributionrelative to the electromagnetic field B_(θ) inside the signal carryingapparatus 101 in the direction of θ=0, 180°. The other direction is ashape that the distribution in the diagram is multiplied by cos θ times.In addition, although the component B_(r) in the radius vector is alsoexistent in the electromagnetic field in the vicinity of the center, itdoes not play a major role in the present invention.

The condition of the current flowing in the first conductor portion 111inside the signal carrying apparatus 101 is shown. Thus, it is ratherconvenient because the electromagnetic wave can be discharged by merelyinducing the current in one direction.

Namely, the electromagnetic field generated by the interface device 601of the embodiment is largely superposed on the electromagnetic field inan asymmetric φ₁ mode, and the electromagnetic field is discharged bymerely inducing the magnetic field or the current in one direction inthe vicinity of the signal carrying apparatus 101. Therefore, it is wellcoupled to the electromagnetic field of the signal carrying apparatus101 generated by the interface device 601 of the embodiment.

The interface devices in the other shapes are further proposed below.FIG. 13 and FIG. 14 are explanatory diagrams each showing a schematicconfiguration of the circular interface device. They are described belowwith reference to the diagram below.

The upper row of the diagram is a bottom view of the interface device601, and the middle row and the lower row are cross-sections. FIG. 14 isa perspective view of the interface device 601.

As shown in the diagram, the external conductor portion 603 of thecircular interface device 601 is of a shape where a cylindrical side isattached to a disc, and a bordering is arranged on the reverse side ofthe disc. The internal conductor portion 602 is connected to thebordering.

In addition, the internal conductor portion 602 penetrates the center ofthe circle and is connected to the path conductor portion 604 at a placeequivalent to the center of the circle.

The path conductor portion 604 penetrates the aperture provided in thevicinity of the center of the external conductor 603.

Then, the region covered with the external conductor is filled withdielectric and includes the insulator portion 605.

In this structure, it is considered that a stable coupling of lessposition dependency is possible even if the interface device 601 isexistent in the mesh anywhere, because it is likely to be coupled with asymmetrical standing wave relative to the central axis of the interfacedevice 601 and can be coupled with both of the φ₁ mode and the axialsymmetrical mode (the mode in which electromagnetic wave radiallytravels at an equal density of energy in all directions from theinterface device 601).

In addition, in the embodiment, it may be also constituted such that theinternal conductor portion 602 is of a cross-shape, the center of thecross-shape is connected to the path conductor 604, and four ends of thecross-shape are connected to the external conductor portion 603.

FIG. 15 is an explanatory diagram showing the other embodiments. Theyare described below with reference to the diagram.

In an example shown in the diagram, the internal conductor portion 602and the path conductor portion 604 are integrated, one loop conductor isconnected at the connection point 606 of the circular external conductorportion 603. A current path may be also secured by looping insidecovered with the external conductor portion 603 functioning as a shieldlike this.

In addition to the afore-mentioned, a form that the internal conductor602 is not connected to the external conductor portion 603 can be alsoconsidered. FIG. 16 is an explanatory diagram showing a relationship ofthe parameters and the conditions of the current and magnetic field insuch a case. It is described with reference to the diagram below.

In the form that the internal conductor portion 602 is not directlyconnected to the external conductor portion 603, as shown in the upperrow of the diagram, it is desirable that the length R of the internalconductor portion 602 is almost half of the wavelength λ. Impedancealignment is arranged by controlling the shortest distance m out of thewidth t of internal conductor portion 602, the distance w between theinternal conductor portion 602 and the external conductor portion 603,and the distance between the contact point between the internalconductor portion 602 and the path conductor portion 604 and the endpoint of the internal conductor portion 602.

The three graphs in the lower row of the diagram show the currentdistribution, magnetic field distribution, and electric fielddistribution. The shape in the graph in FIG. 11 that is further extendedis that of the graph in the diagram.

In the case of the example shown in the diagram, the length of theinternal conductor portion 602 is set at half of the electromagneticwavelength λ. As shown in the diagram, if the impedance z at thedistance x towards near the center of the interface device 601 from theright tip of the internal conductor portion 602 is viewed, although Z=∞because the circuit is opened at x=0, it is Z=0 at x=λ/4.

Therefore, it means the same as a case that the internal conductorportion 602 and the external conductor portion 603 are short-circuitedat a point of x=λ/4. Namely, it can be considered that a loop currentpath is formed by allowing the internal conductor portion 602 and theexternal conductor portion 603 to form a kind of capacitor at thewavelength λ.

FIG. 17 is an explanatory diagram showing the other method for arrangingthe impedance alignment. It is described with reference to the diagram.

As shown in the diagram, the internal conductor portion 602 is decoupledhalfway, and it is determined to be capacitively coupled.

Thus, decoupling the internal conductor portion 602 halfway brings aboutthe same effect as directly connecting a capacitance (typically acapacitor) to the internal conductor portion 602 at an entrance of theinterface device 601.

In these cases, although the current path is decoupled, the vicinity ofa decoupled point results in functioning as a so-called capacitor, anexperiment confirms that it is possible to have an excellent couplingdepending upon frequency bands to be used for communications. Namely,even in such a case, it can be considered that a current loop is formedrelative to a non-direct current component.

In case of the embodiment shown in FIG. 17, there is an advantage thatimpedance alignment is easily arranged by performing the decoupling evenif an external shape of the interface device 601 is small.

In addition, in the case of the embodiments shown in FIG. 16 and FIG.17, the strength of radiation or reception of the electromagnetic waveis determined by the current flowing in the loop structure (includingthe decoupled one) and a path length, and a relative positionalrelationship between the position of decoupling and the signal carryingapparatus 101 does not directly determine the strength.

Thus, in the afore-mentioned embodiment, because the electromagneticwave is dimensionally contained to perform communications, an energyrequired to transmit information to a certain distance is smaller thanthat of a wireless communication.

In addition, it is also possible to supply an electric power because ascope in which the energy is diffused is narrow.

Furthermore, it is considered that a multipath problem can be avoidedand acceleration is possible as compared to the wireless communication.

Moreover, an electrical wiring is not required, and signals can bereceived between the interface device 601 and the signal carryingapparatus 101.

(Experiment Results)

A dielectric of dielectric constant 10 is filled in the region coveredwith the external conduction portion 603 of the interface device 601,and it is determined that the frequency band is 2.4 GHz, R=10 mm, andw=1.6 mm. In addition, for the connection position m of the pathconduction portion 604, it shows an excellent result even in the case ofm=5 mm. However, the below-mentioned shows the experiment result in thecase of m=0 mm. In addition, the mesh cycle d=15 mm.

FIG. 18 is an explanatory diagram showing the experimental parameters ofthe signal carrying apparatus 101 and the interface device 601.

Based on the data in the diagram, two interface devices 601 are disposedat the central distance 10 [cm], 2.4 [GHz] signal of amplitude 1[V] istransmitted from one side to the other. The receiving voltage (S12) whenthe height (position in the z axial direction) of the other interfacedevice 601 is varied is observed. In addition, a 50 [Ω] cable is eachconnected to the interfaces on both sides, and a network analyzer isused to measure the receiving voltage (S12).

In addition, in the data in the diagram, “line width 1 mm and apertureportion side 14 mm of the mesh” are described. These are equivalent tothe values when the repeated unit of the mesh is 15 mm.

FIG. 19 is a graph showing the results. The receiving strength isquickly attenuated until it is deviated by about 0.5 mm.

In the next experiment, the distance between the two interface devices601 is determined to be 6 [cm], three ways of the directions to the meshof the interface device 601 on the reception side are considered. Eachreceiving voltage S12 when signals of 1 V amplitude are inputted by eachfrequency in 1 GHz to 5 GHz is plotted in the graph. A 50Ω cable is eachconnected to two interfaces to measure the receiving voltage (S12) usingthe network analyzer.

FIG. 20 is a graph showing the results. The left end in the lateral axisof the graph is equivalent to 1 GHz and the right end to 5 GHz. As shownin the diagram, the signals are observed in the broad bands, and theavailability of the present invention is confirmed. In addition,individual impedances are shown in the lowest row of the diagram. It isunderstood that impedance in 2.4 GHz band is varied with the directionsof installation, because a coupling between the interface device 601 andthe signal carrying apparatus 101 is strong.

FIG. 21 is a graph in case the position of one interface device 601 ismoved in the afore-mentioned case. As shown in the diagram, sufficientlystrong signals are observed at any positions.

Embodiment 2

The variously modified examples of the afore-mentioned embodiment aredescribed below.

FIG. 22 is an explanatory diagram showing cross-sections of the otherembodiments of the interface device. They are described with referenceto the diagram below.

The interface device 601 described in the lower row of the diagram is aform equivalent to what a combination of the communication device 201and the loop antenna 202 described in FIG. 2 are covered with theexternal conductor portion 603. It can be considered that the openedside (opened portions) of the loop antenna 202 is equivalent to theinternal conductor portion 602, and the external conductor portion 603side of the loop antenna 202 is equivalent to the path conductor portion604.

The interface device 601 described in the middle row of the diagramadopts the communication device 201 in place of the path conductorportion 604, and the external conductor portion 603 and the internalconductor portion 602 are directly connected with the communicationdevice 201.

The interface device 601 described in the upper row of the diagram isthe form of a point that the internal conductor portion 602 and theexternal conductor portion 603 are connected is in the vicinity of theaperture, and is similar to the embodiment shown in FIG. 15.

For the interface device 601 of the present invention, theelectromagnetic field is densely coupled by allowing the internalconductor portion 602 to include a part of the loop and allowing theloop to be vertical to the surface of the signal carrying apparatus 101if the interface device 601 contacts the signal carrying apparatus 101.In this case, the external conductor portion 603 covering these portionsis prepared to prevent the leak of the electromagnetic field.

FIG. 23 is a cross-section showing a relationship between the interfacedevice and a signal carrying apparatus of the other embodiment which isconnectable thereto. It is described with reference to the diagram.

The interface device 601 described in the upper row of the diagram isdisposed in the vicinity of an aperture of the conductive plate 901having the aperture out of the two oppositely disposed conductive plates(may be a sheet-like conductor. Hereinafter is the same) 901. As in theafore-mentioned embodiment, because the electromagnetic wave iscontained between the two conductive plates, signal transmission ispossible and the interface device 601 simultaneously performscommunications through the electromagnetic field that leaks from theaperture.

The interface device 601 described in the lower row of the diagram isthe same as in the afore-mentioned. However, in the embodiment, thelower conductive plate 901 and the conductor 901 of narrower informationwidth than the former are disposed, any of them is extended to intersectwith the diagram, and they are of a strip shape as a whole. Further,they contain the electromagnetic wave in the region sandwiched betweenthe two conductive plates 901. However, because the widths aredifferent, as shown in the diagram, the electromagnetic field leaks at aplace where the lower conductive plate 901 is exposed. Then, theinterface device 601 performs the communications using the phenomenon.

FIG. 24 is an explanatory diagram in case it is connected to the signalcarrying apparatus in wired connection. It is described with referenceto the diagram below.

As shown in the diagram, the width of the wire is controlled so as toalign the impedance just before the junction portion 903 where themeshed first conductor portion 111 of the signal carrying apparatus 101is connected to the core of the coaxial cable 902. In addition, theexternal conductor of the coaxial cable 902 is connected to the secondconductor portion 121.

In addition, in the example shown in the diagram, a striped conductorportion 904 is disposed at the edge of the first conductor portion 111,the electromagnetic wave absorber such as collective resistor isdisposed between the striped conductor portion 904 and the secondconductor portion 121 to prevent the leak of the electromagnetic wave.

FIG. 25 is explanatory diagram showing the embodiment where the firstconductor portion of the signal carrying apparatus is of stripe shape inplace of mesh.

As shown in the diagram, the first conductor portion 111 of the signalcarrying apparatus 101 is disposed on the front side of the diagram ofthe second conductor portion 121, and the first conductor portion 111 isof striped shape that are converged at the root in place of the mesh. Ifthe distance of these stripes is assumed as d, as in the afore-mentionedembodiment, the same leak region as in the afore-mentioned embodimentcan be formed because an extent of leak of the electromagnetic wave isthat of about d.

INDUSTRIAL APPLICABILITY

As stated above, the present invention can provide the signal carryingapparatus for transmitting a signal by variation of electromagneticfield in the interval region sandwiched between the meshed conductorportion and the sheet-like conductor portion and the leak region outsidethe meshed conductor side.

1. A signal carrying apparatus (101) for transmitting signal byvariation of electromagnetic field, comprising a meshed first conductorportion (111) which serves as a conductor in the frequency band of theelectromagnetic field, and a second conductor portion (121) of whichexternal shape is sheet-like and which serves as a conductor in thefrequency band of the electromagnetic field and arranged substantiallyin parallel with the meshed first conductor portion (111); wherein theelectromagnetic field is carried in the frequency band in an intervalregion (131) between the external shape of the first conductor portion(111) and the external shape of the second conductor portion (121), andin a planar leak region (141) located oppositely to the interval region(131) across the external shape of the first conductor portion (111);and wherein a traveling wave component which is affected by the meshedshape out of the electromagnetic field in the leak region (141) has astrength attenuating exponentially with the distance from the externalshape of the first conductor portion (111).
 2. The signal carryingapparatus (101) according to claim 1, wherein the repeated unit lengthof the meshed shape is d, and the thickness of the leak region (141) isd at the biggest.
 3. The signal carrying apparatus (101) according toclaim 1, wherein the mean width of meshes in the meshed shape is d, andthe thickness of the leak region (141) is d at the biggest.
 4. Thesignal carrying apparatus (101) according to claim 1, wherein the meshedshape is a mesh where the same shaped polygon is repeated, and therepeated unit length is d, and a travelling wave component which isaffected by the meshed shape out of the electromagnetic in the leakregion (141) has a strength attenuating at coefficient e^(−2πz/d) orless relative to the distance z from the external shape of the firstconductor portion (111) to the leak region (141).
 5. The signal carryingapparatus (101) according to claim 1, wherein the meshed shape is a meshwhere a plurality of circular holes are provided in a flat plate, andthe central distances of the circular holes are d, and a traveling wavecomponent which is affected by the meshed shape out of theelectromagnetic field in the interval region (141) has a strengthattenuating at coefficient e^(−2πz/d) or less relative to the distance zfrom the external shape of the first conductor portion (111) to the leakregion (141).
 6. The signal carrying apparatus (101) according to claim1 comprising the steps of: transmitting the variation of theelectromagnetic field from the interval region (131) and the leak region(141) to the antenna disposed in the leak region (141) or transmittingthe variation of the electromagnetic field from the antenna to theinterval region (131) and the leak region (141) to communicate with anexternal device connected to the antenna.
 7. The signal carryingapparatus (101) according to claim 6 comprising the steps of:transmitting the varied voltage between the first conductor portion(111) and the second conductor portion (121) with the electromagneticfield in the interval region (131) and the leak region (141) to acommunication device connected to the first conductor portion (111) andthe second conductor portion (121) in wired connection, or transmittingthe signal between the communication device and the external device byvarying the voltage the first conductor portion (111) and the secondconductor portion (121) to vary the electrostatic field in the intervalregion (131) and the leak region (141).
 8. The signal carrying apparatus(101) according to claim 1, wherein the second conductor portion (121)is of a meshed shape, and further transmits the electromagnetic field inthe frequency band in the opposite region (151) of planar shape locatedoppositely to the interval region (131) across the external shape of thesecond conductor portion (121).
 9. The signal carrying apparatus (101)according to claim 1, wherein the first conductor portion (111) is of astriped shape in place of a meshed shape.